What causes spider veins?
Spider veins are usually caused by venous insufficiency; they are a symptom of veins deeper down in the leg or in the body backing up with blood. In this video, cardiothoracic surgeon David Greuner, MD, explains exactly how spider veins develop.
Up next
Jan 14, 2026
Everything you need to know about varicose veins
Oct 30, 2013
What are varicose veins?
Nov 12, 2012
How can I prevent varicose veins and spider veins?
What increases my risk of having varicose veins?
Jan 10, 2013
Can varicose and spider veins return even after treatment?
Dec 10, 2012
How are varicose veins diagnosed?
What procedures help treat varicose veins?
Nov 14, 2012
How is sclerotherapy performed?
What is cryo-sclerotherapy?
Dr. Steve Elias - what is sclerotherapy?